A magnetic recording medium using a polymer support is advantageous in that the recording medium has a proper flexibility and the roughness of the surface can be properly controlled. However, such a support can cause changes due to thermal shrinkage.
The thermal shrinkage means an irreversible dimensional change occurring when using, preserving, or transporting a magnetic recording medium in a high temperature atmosphere.
When the dimensional change occurs between recording and reproducing, a tracking discrepancy occurs reducing reproduction output and, in an extreme case, makes reproduction impossible.